I started my bike today and heard a faint clattering sound - quickly chased it to the shield on the silencer. One of the three hex-head screws securing it was gone. I went to the hardware store with allen wrench in hand (pocket, actually), and removed a second screw to find a match. It came out with little difficulty, with threads slightly surface-rusty but otherwise intact. The shortest replacement I could find was just a hair longer than the original.

I put both back on the bike (they both went on fairly easily), and sure enough, the longer screw bottomed out just before the head clamped down on the shield. I thought I'd grab a washer to fill the gap, but... darned if I could get either screw back out again. After I got home, I waited for things to cool down a bit, then went after both screws with penetrating oil, all the while thinking I was going to strip the hex socket or break the tool (not likely to break the head off the 6mm screw). I eventually got them both out, with threads intact, but what the heck is going on here? I was going to lock-tite them, but now everything is saturated with penetrating oil. Anyway, I don't see how they would have come out on their own as tight as they were.

Ideas?

Will residual penetrating oil bother blue lock-tite? Will blue lock-tite work at all with the heat of the exhaust?

I threw those silly little allen head screws away the first time I got them out. I replaced them with standard hex head bolts in stainless steel. I had to cut them down a bit but that was easy enough with a Dremel. Now when I need to take them out past the accumulated rust I know I can get enough torque to do it.

The residual oil will block Loc-Tite. Just use some solvent and a Qtip to clean them out. At those temps no LocTite is going to hold BUT it will fill the gap with it's plasticky-ness and help prevent more rust.

The Loctite will work, but a better plan is to get a different muffler. I had the same problem with my stock muffler the day I picked it up. I heard the rattling but kinda dismissed it, and a few weeks later, got an EFI muffler and when removing the bazooka, found the heat shield screws loose.Bare

I doubt that Loc-Tite will last in that area of the muffler.Based on the colors of the chrome plating I would guess it could get well over 700 degrees F.A heavy split lock washer would probably do a better job of securing the screws.